Full size underbody blankets are known. One such is disclosed in US publication 2006/0052851 and its divisional publication US 2011/0098794. The '851 publication discloses a full size underbody blanket that has two longitudinal seals with perforations therealong that enable those seals to be opened so that the arms of the patient may be extended there through. The problem with such a scheme is that there are times that it may be difficult to tear the elongate seals since a patient is lying thereon. Also, the placement of the blanket onto the surgical bed may require the pulling of the blanket along the surgical bed. This may cause the tearing of the seals and thus may affect the handling of the blanket.